1. Field of the Invention
The present invention relates generally to contraception, and more particularly to intrafallopian contraceptive devices and nonsurgical methods for their delivery.
Worldwide demand exists for safe, effective methods of both contraception and permanent sterilization. Although a variety of contraception and sterilization methods are available, all of the existing methods have limitations and disadvantages. Thus, the need for additional safe, low cost, reliable methods of contraception and permanent sterilization, both in developed and less developed countries, is widely recognized.
Many presently available contraception methods require significant user involvement, and user non-compliance results in quite high rates of failure. While the theoretical effectiveness of existing contraceptives, including barrier methods and hormonal therapies, is well established, overcoming user noncompliance to improve overall efficacy has proven difficult.
One form of contraception which is less susceptible to user noncompliance is the intrauterine device (IUD). IUDs have been found to have higher rates of reliability, and are effective for a longer period of time, than most other commercially available contraceptives. Unfortunately, IUDs are also associated with serious infectious complications. For this reason, the use of IUDs within the United States has decreased dramatically. Additionally, IUDs are subject to unplanned expulsion, and must be removed due to excessive pain or bleeding in a percentage of cases, further reducing the acceptance of the IUD as a contraceptive method. Interestingly, the efficacy of copper IUDs appears to be higher than that of non-metallic IUDs. The reason for this has not been fully explained.
Commercially available options for permanent sterilization include fallopian tube ligation and vasectomy. These methods are surgical, are difficult to reverse, and are not available to many people in the world. It is common knowledge that fertilization occurs in the fallopian tubes where the sperm and ovum meet. Tubal ligation avoids this by complete occlusion of the fallopian tubes.
It has previously been proposed to reversibly occlude the fallopian tubes, for example, by in vitro formation of an elastomeric plug, or otherwise anchoring a device on either side of the narrowest region of fallopian tube, called the xe2x80x9cisthmus.xe2x80x9d Such fallopian tube occlusion methods appear promising; however, an unacceptably high percentage of the non-surgical devices proposed to date have become dislodged during previous studies. Even where non-surgical intrafallopian devices have remained in place, they have been found to be only moderately effective at preventing conception.
For these reasons, it would be desirable to provide effective, reliable intrafallopian devices for contraception and sterilization. It would be particularly desirable to provide highly effective intrafallopian devices which did not require surgery for placement. It would be especially desirable if such devices and methods allowed easy placement of the device, but were less susceptible to being dislodged than previously proposed non-surgical intrafallopian devices.
2. Description of the Related Art
The experimental use of a stainless steel intrafallopian device is described in Transcatheter Tubal Sterilization in Rabbits, Penny L. Ross, RT 29 xe2x80x9cInvestigative Radiologyxe2x80x9d, pp. 570-573 (1994). The experimental use of an electrolytically pure copper wire as a surgical contraceptive intrafallopian device in rats was described in xe2x80x9cAntifertility Effect of an Intrafallopian Tubal Copper Devicexe2x80x9d, D. N. Gupta, 14 Indian Journal of Experimental Biology, pp. 316-319 (May 1976).
U.K. Patent Application Pub. No. 2,211,095 describes a uterine screw plug for blocking the fallopian tube. European Patent Application Pub. No. 0,010,812 describes a device for placement in the oviducts having enlargements at either end for anchoring the device. The same device appears to be described in Netherlands Patent No. 7,810,696.
The use of tubal occlusion devices is described in xe2x80x9cHysteroscopic Oviduct Blocking With Formed-in-Place Silicone Rubber Plugsxe2x80x9d, Robert A. Erb, Ph.D., et al., The Journal of Reproductive Medicine, pp. 65-68 (August 1979). A formed-in-place elastomeric tubal occlusion device is described in U.S. Pat. No. 3,805,767, issued to Erb. U.S. Pat. No. 5,065,751, issued to Wolf, describes a method and apparatus for reversibly occluding a biological tube. U.S. Pat. No. 4,612,924, issued to Cimber, describes an intrauterine contraceptive device which seals the mouths of the fallopian tubes.
German Patent No. 28 03 685, issued to Brundin, describes a device for plugging a body duct with a device which swells when in contact with a body fluid.
Alternative contraceptive devices are disclosed in co-pending U.S. patent application Ser. No. 08/474,779, the full disclosure of which is herein incorporated by reference.
The present invention provides intrafallopian devices and methods for their placement to prevent conception. The intrafallopian devices of the present invention are transcervically delivered and mechanically anchored within the fallopian tube to provide long term contraception, or alternatively permanent sterilization, without the need for surgical procedures or the risks of increased bleeding, pain, and infection associated with intrauterine devices (IUDs).
The intrafallopian devices of the present invention will often comprise a structure having a lumen-traversing region with a helical outer surface. The helical surface is mechanically anchored by a resilient portion of the structure which is biased to form an enlarged secondary shape, preferably forming distal and proximal anchoring loops. The anchoring loops help prevent the helical outer surface from rotating out of position, and also directly deter axial motion within the fallopian tube. In alternative embodiments, anchoring may be provided by a straight coil which is resiliently deflected by the axial curvature of the tortuous fallopian tube, and a radially expandable braid, malecott, or some other tubular structure may help affix the device within the fallopian tube.
The use of copper in the intrafallopian device of the present invention improves its efficacy as a contraceptive method. Devices formed from plastically deformable materials, however, are less readily restrained in the fallopian tube. Apparently, the large variation in the actual shape and dimensions of fallopian tubes does not provide reliable anchoring for a pre-formed deformable intrafallopian device. The intrafallopian device of the present invention therefore often comprises a resilient structure, usually a metallic coil, which includes a copper alloy or plating, ideally comprising an alloy including at least 75% copper. The coil material typically includes beryllium, zinc, stainless steel, platinum, a shape memory alloy, such as Nitinol(copyright), or the like. Preferably, the coil is composed of an alloy of beryllium and copper.
Although the present device will generally result in occlusion, it need not completely occlude the fallopian tube to prevent the meeting of the sperm and ovum. Instead, in some embodiments, the presence of the copper on the resilient structure is sufficient to provide effective contraception. Hence, contraception can be provided by disrupting the normal architecture and/or function of the fallopian tube, despite the presence of an open lumen. This concept is referred to herein as xe2x80x9cfunctional occlusionxe2x80x9d. As used herein, a device which provides functional occlusion means that the device, when implanted in the fallopian tube, disrupts the normal architecture and/or functioning of the fallopian tube so as to inhibit fertilization and/or conception.
Conveniently, the present invention further comprises non-surgical placement of such intrafallopian devices by transcervical introduction. The resilient structure is restrainable in a straight configuration, e.g., by use of a corewire, greatly facilitating and reducing the risks of introduction. Thus, the cost and dangers associated with existing surgical contraceptive and sterilization procedures are avoided.
In a first aspect, a contraceptive intrafallopian device according to the present invention comprises a proximal anchor, a distal anchor, and a lumen-traversing region extending between the anchors. The lumen traversing region has a helical outer surface and a cross-section which is smaller than the cross-sections of the proximal and distal anchors.
Preferably, the lumen-traversing region comprises a resilient structure, generally having a ribbon wound over the outer surface to form the helical shape. Anchoring is enhanced by a sharp outer edge on the ribbon. As described above, at least one of the proximal anchor, the distal anchor, and the lumen-traversing region preferably comprises copper. The proximal and distal anchors generally comprise a resilient structure biased to form an enlarged secondary shape, thereby allowing the device to be restrained in a straight configuration to facilitate transcervical introduction.
In another aspect, a contraceptive intrafallopian device according to the present invention comprises a primary coil having a proximal loop, a distal loop, and an intermediate straight section between the loops. A helical ribbon is wound over at least a portion of the intermediate section, forming a helical surface to mechanically anchor the device within the fallopian tube. An element is disposed along the coil, and is adapted to incite a tissue reaction in the tubal tissues which inhibits conception.
The ribbon of the present intrafallopian device generally protrudes sufficiently to firmly engage the tubal wall. Preferably, the ribbon has a width in the range between 0.005 and 0.1 inch, a thickness in the range between 0.001 and 0.2 inch, and a pitch in the range between 0.01 and 0.2 inch. The overall device geometry preferably facilitates introduction and retention, but is not large or rigid enough to interfere with internal tissue movements. Usually, the device has a length in the range between 1.5 cm and 7.5 cm when in a relaxed state, while the distal loop and the proximal loop have outer diameters of at least 3.0 mm. Preferably, the primary coil has an outer diameter in the range between 0.2 mm and 5.0 mm.
In another aspect, a system for delivering intrafallopian contraceptive devices according to the present invention comprises a primary coil having a proximal loop, a distal loop, and an intermediate straight section between the loops. Additionally, a lumen extends from a proximal end of the proximal loop to near a distal end of the distal loop. A helical ribbon is wound over at least a portion of the intermediate section, forming a helical surface to mechanically anchor the device within the fallopian tube. A corewire is removably disposed within the lumen of the primary coil. The corewire restrains the primary coil in a straight configuration, facilitating transcervical introduction. Optionally, the corewire is threadably received by the primary coil. Alternatively, a release catheter is slidably disposed over the corewire proximally of the primary coil to restrain the primary coil while the corewire is withdrawn proximally from the fallopian tube.
The helical ribbon is anchored in the fallopian tube by the distal and proximal loops. The ribbon is set in the tubal wall while the device is restrained in a straight configuration over a corewire by torquing on the corewire. Withdrawing of the corewire then releases the anchors. The distal anchor may be inserted into the ampulla, distal of the isthmus, while the proximal anchor is located in the ostium. These anchors prevent rotation of the device, and also help avoid axial movement. Alternatively, the anchors may be positioned anywhere past the ostium and within the fallopian tube, depending on their length and configuration. Preferably, at least some anchoring is provided along the intramural to isthmic region of the fallopian tube.
In yet another aspect, an intrafallopian contraceptive method according to the principles of the present invention comprises restraining a resilient contraceptive structure in a straight configuration over a corewire, where the resilient structure includes a lumen-traversing region having a helical outer surface. The resilient structure is transcervically introduced into a target region of a fallopian tube, typically in the region of the ostium, and the corewire is withdrawn from the resilient structure. The resilient structure is mechanically anchored within the fallopian tube, a portion of the resilient structure assuming an enlarged secondary shape which is larger in cross-section than the fallopian tube. Optionally, an electric current is applied through the resilient structure to the fallopian tube, thereby effecting permanent sterilization. In fact, such electrosurgical attachment of an intraluminal device to a surrounding lumenal wall may provide effective anchoring even without loops and other anchoring structures. Electrical current may also be used to decouple the intrafallopian device from the delivery system, typically by electrolytically dissolving a solder bond. Current may also actuate an anchor, such as by releasing a resilient radially expandable tubular structure within the fallopian tube.
Tissue Reaction
The present invention also provides improved contraceptive devices which incite a tissue reaction within the fallopian tube to prevent conception. This group of intrafallopian devices will often make use of a highly flexible coil structure to avoid damaging or penetrating through the delicate tubal tissues. The desired tissue reaction may be the result of the material of intrafallopian device, or may be incited by a coating, a surface treatment, a mechanical interaction between the device and the surrounding tubal wall, or the like. The tissue will often help impede conception by occluding the fallopian tube, by interrupting the transport mechanisms of the tubal tissues, and/or by restraining the intrafallopian tubal device within the tube. Specific tissue reactions which may provide these intended results include tissue ingrowth into the contraceptive device and/or the tubal lumen, scar tissue formation, sclerosing of the tubal tissues, and the like.
In one aspect, the invention provides a tissue reaction contraceptive device for use in a fallopian tube. The contraceptive device comprises a coil having a proximal end and a distal end and defining an axis therebetween. The coil is axially flexible and has a cross-section suitable for insertion into the fallopian tube. An element disposed along the coil is adapted to incite a tissue reaction in the tubal tissues adjacent the coil so as to inhibit conception.
In some embodiments, the element may promote ingrowth of the tubal tissues into the contraceptive device. For example, the element may include a braided or woven polyester, a micro-porous material or surface treatment, or the like. Alternatively, a sharp edged helical ribbon or other mechanical interaction element may incite the formation of scar tissue, or a surface coating of the coil may sclerose the tubal tissues, exciting formation of tough fibrous connective tissues which interfere with conceptive transport. In many embodiments, the presence of the contraceptive device in combination with the tissue reaction can provide effective contraception without having to rely on total occlusion of the fallopian tube.
In another aspect, the present invention provides a tissue ingrowth contraceptive device for use in a fallopian tube. The contraceptive device comprises a tubular retention structure having a proximal end, a distal end and an axis therebetween. The retention structure is axially flexible, and is insertable within the fallopian tube. A material which can incite ingrowth of the tubal tissue is attached to, and exposed radially from, the retention structure.
In the exemplary embodiment, the retention structure comprises a helical coil in which the ingrowth material is disposed. Such helical coils may optionally be radially expansible within the fallopian tube, thereby allowing the device to accommodate a wide variety of tubal physiologies. The ingrowth material may be in the form of braided or woven fibers of polyester, P.T.F.E., or the like.
In another aspect, the present invention provides a tissue ingrowth contraceptive device for use in a fallopian tube. The contraceptive device comprises a resilient elongate body having a proximal end and a distal end and defining an axis therebetween. A retention structure is disposed along the resilient body. The retention structure is adapted to restrain the resilient body within the fallopian tube. A bond affixes the retention structure to the resilient body. At least one of the resilient body, the retention structure, and the bond comprises a micro-porous material which promotes tissue ingrowth therein.
In another aspect, the present invention provides a contraceptive method comprising transcervically inserting a contraceptive device within a fallopian tube. The device is inserting by resiliently deflecting a distal body of the contraceptive device against a tubal wall, so that the distal body guides the contraceptive device axially along the fallopian tube. A tissue reaction is incited with an element of the contraceptive device in the tubal tissues. This tissue reaction affixes the contraceptive device within the fallopian tube.
One Size Fits All
The present invention also provides improved contraceptive devices, systems, and methods adapted for use in the widely varying geometry of the fallopian tube. In recognition of the wide variations in tubal physiology, the contraceptive structures of the present invention are radially expandable within the fallopian tube to engage the tubal wall. Surprisingly, the contraceptive devices of the present invention will often make use of tubular structures such as resilient helical coils. Such tubular devices will often effect contraception by disrupting the architecture and/or transport mechanisms of the tubal tissues, rather than relying entirely on total blockage of the tube. The passages through the tubular contraceptive devices of the present invention may optionally be occluded by promoting tissue ingrowth within the device, for example, by including woven or braided polyester fibers within a helical coil. Regardless, such tubular retention structures are capable of radially expanding against tubal walls throughout a wide range of tubal sizes to safely anchor the contraceptive device, without having to resort to protruding barbs or the like.
In one aspect, the present invention provides a contraceptive device for use in fallopian tube having a tubal wall. The contraceptive device comprises a tubular retention structure having a proximal end, a distal end, and an axis therebetween. The retention structure is radially expandable in situ from a narrow configuration (in which the retention structure has a first diameter which is suitable for axial insertion into the fallopian tube) so as to define a second, enlarged diameter. The expanded retention structure is adapted to engage the surrounding tubal wall and retain the contraceptive device within the fallopian tube.
In another aspect, the present invention provides a contraceptive device for use in a fallopian tube having a tubal wall. The contraceptive device comprises a conception inhibiting body which defines an axis. A helical coil is disposed about the body. A portion of the helical coil is movable relative to the body so that the helical coil can expand resiliently throughout a range of tubal cross-sectional sizes. Hence, the coil can radially engage the surrounding tubal wall and safely affix the contraceptive device within the fallopian tube.
Straight Coil
The present invention also provides intrafallopian contraceptive devices having elongate coils which are substantially straight. Surprisingly, when such straight coils are positioned axially within the tortuous fallopian tubes, the bends imposed on the coil by the fallopian tube can result in resilient anchoring of the coil. Such straight coils are also highly advantageous when advancing the contraceptive device into (and within) the fallopian tube. Straight resilient coils can act as an integral guidewire during transcervical deployment of the device within the fallopian tube, thereby avoiding the delay associated with the sequential use of guidewires, tubal axis catheters, and the like.
The present invention provides an intrafallopian contraceptive device for use in a fallopian tube. The contraceptive device comprises an elongate coil having a proximal end, a distal end, and an axis therebetween. The axis is substantially straight when the coil is at rest, and the coil is axially resilient to facilitate insertion of the body axially into the tube. The device is adapted to be retained within the fallopian tube so as to inhibit conception.
In another aspect, the present invention provides an intrafallopian contraceptive device for use in a fallopian tube. The tube has a tubal wall with a tubal cross-section and an axial curvature. The contraceptive device comprises an elongate body having a proximal end and a distal end and defining an axis therebetween. The body has a cross-section suitable for axial insertion within the tubal cross-section. At least a portion of the body is straighter than the axial curvature of the fallopian tube. The body is sufficiently flexible to deflect against the tubal wall without injuring the tubal wall. The body is also sufficiently resilient to impose an anchoring force against the tubal wall when the straight portion flexes along the axial curvature of the fallopian tube.
In another aspect, the present invention provides a contraceptive device for use in a fallopian tube having an axis. The contraceptive device comprises a structure having a proximal end, a distal end, and an axis therebetween. The structure is adapted to provide effective tubal occlusion when disposed substantially coaxially within the fallopian tube. An elongate member is affixed to the occlusion structure. The member extends distally of the occlusion structure and is sufficiently flexible and axially resilient to help guide distal advancement of the occlusion structure within the fallopian tube.
In a contraceptive method provided by the present invention, an elongate resilient body is transcervically inserted into an axially curving fallopian tube so that the fallopian tube imposes an axial bend on the body. The bent body imposes an anchoring force which helps anchor the bent body within the fallopian tube. The body is anchored within the fallopian tube so that the affixed resilient body inhibits conception.
In another aspect, the present invention provides a contraceptive method comprising transcervically inserting an intrafallopian contraceptive device along the fallopian tube by guiding the contraceptive device with a distal guidewire-like structure of the contraceptive device. The device, including at least a portion of the guidewire-like structure, is retained within the fallopian tube so that the device inhibits conception.
In another aspect, the present invention provides a contraceptive kit. The kit comprises an intrafallopian contraceptive device and instructions for its use. The instructions describe and/or set forth the method steps of transcervically introducing the contraceptive device into a fallopian tube and affixing the contraceptive device within the tube. Optionally, a variety of delivery structures may also be provided in the kit, including guidewires, corewires, delivery catheters, and the like.